There is known a practice to add a dopant trace element to a material for the purpose of developing material function or improving high-temperature properties. Comprehension of the cause of functionality development requires substitution site measurement for determining whether or not the dopant element is substituted in a main phase and for determining in which site in a crystal structure of the main phase the dopant element is substituted. An example of crystal structure model having substitution sites is shown in FIG. 19. The figure shows an exemplary face-centered cubic structure where an A atom is located at an A site as each vertex of a unit lattice while a B atom is located at a B site as the center of each face. Further, a C atom is substituted in a C site (substitution site) as one of the B sites. Heretofore, the measurement of substitution site has been taken by means of synchrotron radiation XAFS (X-ray Absorption Fine Structure) or neutron diffraction. In the method using the radiation beam or neutron diffraction, a beam size ranging from several dozen micrometers to several millimeters makes it difficult to evaluate the measurement in a unit of micron-sized main phase. In a synchrotron radiation facility, on the other hand, the limitation of machine time makes it difficult to evaluate the substitution site measurement on a short TAT (Turn Around Time) basis.
In a method using a transmission electron microscope (TEM), the size of electron beam can be reduced to a nanometer order. Hence, the method permits the substitution site measurement on a micron-sized particle basis. Further, the method also permits the substitution site measurement on the short TAT basis for a laboratory measurement operation.
In the substitution site measurement using the electron beam, the substitution site measurement is taken on the basis of dependency of X-ray amount on incidence angle of electron beam, the X-ray generated from a specimen upon incidence of the electron beam on the specimen. When the electron beam is incident on the specimen, the electron beam interferes with transmitted waves and diffracted waves in the specimen (electron beam diffraction effect) so that standing waves of the electron are generated in the specimen. A large amount of X-ray is generated in an atomic row where the standing waves are generated. If the standing waves are generated in the row of A atoms in the case of an incidence azimuth 1, for example, a large amount of A-atom X-ray is generated. If the standing waves are generated in the row of B atoms in the case of an incidence azimuth 2, a large amount of B-atom X-ray is generated. In a case where the C atoms substitute for some of the A atoms, C-atom X-ray is increased when the beam is incident in incidence azimuth 1, while the C-atom X-ray is decreased when the beam is incident in incidence azimuth 2. As just described, the substitution site measurement can be taken by changing the azimuth of the incident electron beam and detecting the X-ray generated from the specimen. The above-described substitution site measurement using the electron beam and the X-ray is devised by Tafϕ and Spence in 1982 and is called ALCHEMI (Atom location by channeling-enhanced microanalysis) (Non-patent Literature 1).